1. Field
The present invention generally relates to communications in a wireless environment. More particularly, the invention relates to optimizing paging/sleep cycles in a wireless communication system.
2. Background
Wireless communication systems developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5G and 2.75G networks) and a third-generation (3G) high speed data/Internet-capable wireless service. There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Examples of known cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), the Global System for Mobile access (GSM) variation of TDMA, and newer hybrid digital communication systems using both TDMA and CDMA technologies.
The method for providing CDMA mobile communications was standardized in the United States by the Telecommunications Industry Association/Electronic Industries Association in TIA/EIA/IS-95-A entitled “Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,” referred to herein as IS-95. Combined AMPS & CDMA systems are described in TIA/EIA Standard IS-98. Other communications systems are described in the IMT-2000/UM, or International Mobile Telecommunications System 2000/Universal Mobile Telecommunications System, standards covering what are referred to as wideband CDMA (WCDMA), CDMA2000 (such as CDMA2000 1xEV-DO standards, for example) or TD-SCDMA.
In wireless communication systems mobile devices (referred to as mobile stations, handsets, access terminals, and/or user terminals) receive signals from fixed position base stations (also referred to as cell sites or cells) that support communication links or service within particular geographic regions adjacent to or surrounding the base stations. In order to aid in providing coverage, each cell is often sub-divided into multiple sectors, each corresponding to a smaller service area or geographic region. An array or series of base stations placed adjacent to each other form a communication system capable of servicing a number of system users, over a larger region.
Typically, each mobile station monitors a control channel that can be used to exchange messages between the mobile station and the base station. The control channel is used to transmit system/overhead messages, whereas traffic channels are typically used for substantive communication (e.g., voice and data) to and from the mobile station. For example, the control channel can be used to establish traffic channels, control power levels, and the like, as is known in the art.
Additionally, since the mobile stations are typically battery operated, power conservation is emphasized in the system design. Accordingly, mobile stations can go into sleep cycles and periodically awaken to monitor the control channel for messages/paging directed to the mobile station. However, the responsiveness of the communication system can suffer because the sleep state imposes additional delay in establishing communications to the mobile station. The degradation of the system responsiveness increases as the duration of the sleep cycles increases. In systems with long sleep cycles, the system responsiveness may not be acceptable for all applications. Accordingly, system engineers may face a trade-off between poor power conservation and poor responsiveness.